You're looking at the earliest known drawings of Mickey Mouse, cir. 1928 (Edit 5/2/12 - by Ub Iwerks, Thanks Byron!).
It's interesting to note that Walt Disney already had Mickey's circular
ears down pat even in the early sketches.

Sorry for the geek moment here but Mickey Mouse was first drawn by Ub Iwerks. Not Disney. You can read all about the history in the book 'The Hand Behind the Mouse' by (Leslie Iwerks, the daughter of Ub, and John Kenworthy)